Wow, I must say, if you cannot do those questions, then you are certainly not ready for your math exam

1. if the y-intercept is 0, doesn't that mean the line goes through the origin or (0,0) ????
so in y = mx + b form ...
y = (-1/5)x
multiply by 5
5y = -x
standard form has both x and y terms on the left, constants on the right, so
x + 5y = 0